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United States Patent |
5,028,038
|
de Fontenay
|
July 2, 1991
|
Elastic vibration isolation mounting with integral hydraulic damping and
a rigid partition with an adjustable passage for conducting fluid
Abstract
Elastic anti-vibration isolation apparatus with integrated hydraulic
damping, consisting of a thick conical membrane of elastomer compound
bonded to internal and external rigid frames, and crimped in a casing
containing a damping liquid, characterized by the fact that the rigid
partition which separates the variable volume chamber from the expansion
space has a passage for the damping liquid realized in one or two parts,
the dimensions of which can be adjusted by grinding or lathe-working at
least one of the components, base or cover, of the rigid partition, or by
the insertion of shims between the constituent parts, thereby making it
possible, using a set of similar components, to realize a range of elastic
mountings with damping characteristics adapted to desired utilization
frequencies.
Inventors:
|
de Fontenay; Etienne (Decize, FR)
|
Assignee:
|
Caoutchouc Manufacture et Plastiques (Versailles, FR)
|
Appl. No.:
|
475338 |
Filed:
|
February 5, 1990 |
Foreign Application Priority Data
Current U.S. Class: |
267/140.13; 138/30; 138/43; 180/312 |
Intern'l Class: |
F16F 013/00 |
Field of Search: |
267/140.5 R,140.1 A,220
248/562,636
180/300,312,902
138/30,43
123/192 R
|
References Cited
U.S. Patent Documents
4422779 | Dec., 1983 | Hamaekers et al. | 267/140.
|
4618128 | Oct., 1986 | Hartel et al. | 267/140.
|
4681306 | Jul., 1987 | Hofmann et al. | 267/140.
|
4699099 | Oct., 1987 | Arai et al. | 123/192.
|
4709898 | Dec., 1987 | Yoshida et al. | 267/140.
|
4754956 | Jul., 1988 | Barone et al. | 267/140.
|
Foreign Patent Documents |
0155646 | Sep., 1985 | EP.
| |
0192782 | Sep., 1986 | EP.
| |
0209682 | Jan., 1987 | EP.
| |
3611529 | Oct., 1987 | DE.
| |
2430546 | Jul., 1978 | FR.
| |
2467724 | Apr., 1981 | FR.
| |
2443615 | Jan., 1983 | FR.
| |
2462618 | Apr., 1984 | FR.
| |
2575253 | Jun., 1986 | FR.
| |
2511105 | Sep., 1986 | FR.
| |
9117930 | Jul., 1984 | JP.
| |
61-52439 | Mar., 1986 | JP.
| |
61-55426 | Mar., 1986 | JP.
| |
1144443 | Jul., 1986 | JP.
| |
1205503 | Sep., 1986 | JP.
| |
2191561 | Dec., 1987 | GB.
| |
Primary Examiner: Halvosa; George A.
Attorney, Agent or Firm: Ljungman; Thomas N.
Parent Case Text
This is a division, of application Ser. No. 07/177,583, filed on Apr. 4,
1988, now U.S. Pat. No. 4,909,490.
Claims
What is claimed is:
1. An elastic antivibration isolation apparatus having hydraulic damping,
said isolation apparatus for being interposable between a first component
and a second component which vibrates relative to said first component and
comprising:
a substantially rigid external frame comprising a first mounting means for
mounting said isolation apparatus on said first component;
second mounting means for mounting said isolation apparatus on said second
component, said second mounting means comprising a substantially rigid
member;
an elastomeric element interconnecting said substantially rigid external
frame and said second mounting means and providing relative movement
therebetween through flexure of said elastomeric element;
an internal cavity located substantially within said external frame;
a substantially rigid partition substantially dividing said internal cavity
into a first chamber and a second chamber, the volume of said first
chamber being alterable through flexure of said elastomeric element, said
second chamber comprising an expansion space, said first chamber and said
expansion space being substantially filled with a damping fluid, and said
substantially rigid partition comprising at least one throughgoing passage
for providing communication of said damping fluid between said first
chamber and said expansion space; substantially said rigid partition
comprising:
a base member; and
a cover member;
said base and cover members having opposing faces;
at least one of said base and cover members having at least two spiral
grooves formed on its corresponding opposing face;
each of said at least two spiral grooves separately comprising at least a
portion of said throughgoing passage, each of said at least two spiral
grooves being for providing said communication of said damping fluid
independently of any other of said at least two spiral grooves, each of
said at least two spiral grooves comprising a first end and a second end,
said first end of each of said at least two spiral grooves communicating
solely with said first chamber and said second end of each of said at
least two spiral grooves communicating solely with said second chamber;
and
means for varying the length of at least one of said at least two spiral
grooves independently of the length of any other of said at least two
spiral grooves to thereby tune the damping characteristics of said elastic
antivibration isolation apparatus to at least one frequency
characteristic;
said length varying means comprising at least one hole provided in at least
one of said base and cover members, proximate the center thereof, and
intersecting each of said at least two spiral grooves at an inwardmost
extremity thereof, the diameter and position of said at least one hole
determining said length of each of said at least two spiral grooves and,
at least in part, the damping characteristics of said elastic
antivibration isolation apparatus.
2. An antivibration isolation apparatus according to claim 1, wherein said
hole is disposed tangentially with respect to at least one of said at
least two spiral grooves.
3. An antivibration isolation apparatus according to claim 2, wherein said
at least one of said at least two spiral grooves extends more than one
full revolution within said rigid partition.
4. An antivibration isolation apparatus according to claim 2, wherein said
hole is asymmetrically positioned with respect to said at least two spiral
grooves such that the effective lengths of said at least two spiral
grooves substantially differ from one another.
5. An antivibration isolation apparatus according to claim 4, wherein said
at least one of said at least two spiral grooves extends more than one
full revolution within said rigid partition.
6. The antivibration isolation apparatus according to claim 5, further
including means for varying the length of two of said at least two spiral
grooves, said length varying means comprising said at least one hole
provided in at least one of said base and cover members.
7. An antivibration isolation apparatus according to claim 1 wherein said
at least one of said at least two spiral grooves extends more than one
full revolution within said rigid partition.
8. A method for tuning a plurality of elastic antivibration isolation
apparatuses having hydraulic damping, each of said plurality having
identical components, said plurality of isolation apparatuses comprising
different groups, each of said groups having different frequency
characteristics, said isolation apparatus for being interposable between a
first component and a second component which vibrates relative to said
first component, each said elastic antivibration isolation apparatus
comprising:
a substantially rigid external frame comprising a first mounting means for
mounting said isolation apparatus on said first component;
a second mounting means for mounting said isolation apparatus on said
second component, said second mounting means comprising a substantially
rigid member;
an elastomeric element interconnecting said substantially rigid external
frame and said second mounting means and providing relative movement
therebetween through flexure of said elastomeric element;
an internal cavity located substantially within said external frame;
a substantially rigid partition substantially dividing said internal cavity
into a first chamber and a second chamber, and volume of said first
chamber being alterable through flexure of said elastomeric element, said
second chamber comprising an expansion space, said first chamber and said
expansion space being substantially filled with a damping fluid, and said
substantially rigid partition comprising at least one throughgoing passage
for providing communication of said damping fluid between said first
chamber and said expansion space;
said substantially rigid partition comprising:
a base member; and
a cover member;
said base and cover members having opposing faces;
at least one of said base and cover members having at least one spiral
groove formed on its corresponding opposing face and comprising a portion
of said throughgoing passage;
said at least one spiral extending around more than one full revolution and
said method comprising the steps of:
starting with identical components;
assembling the identical components of the base members and the cover
members to form different groups of said substantially rigid partitions;
machining a hole having at least one of:
a different diameter and
a different location in each of the different groups of said substantially
rigid partitions to vary the length of said at least one spiral groove in
a plurality of said identical components during manufacture;
assembling during manufacture each of said different groups elastic
antivibration isolation apparatuses to tune the damping characteristics of
different groups of said elastic antivibration isolation apparatus to at
least one different frequency; and
said at least one spiral groove comprising at least two grooves in the form
of a double spiral.
9. The method according to claim 8, including positioning said hole
asymmetrically with respect to said at least two spiral grooves forming
said double spiral, such that the effective lengths of said at least two
spiral grooves substantially differ from one another.
10. The method according to claim 8, wherein said at least one of said at
least two spiral grooves extends more than one full revolution within said
rigid partition.
11. The method according to claim 8, wherein said hole is disposed
tangentially with respect to at least one of said at least two spiral
grooves.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to anti-vibration, isolation devices for machines,
in particular elastic mountings for automobile motors or the cabs of large
trucks. It relates to high-flexibility mountings with integrated hydraulic
damping, increasing the apparent rigidity in a very limited range of
rather low frequencies, by means of a column of liquid which is very long
in relation to its cross section. The resonance of this column counteracts
large amplitude displacements, but does not deleteriously affect, to any
substantial degree, the elastic filtering a higher frequencies.
A range of such elastic mountings is generally made possible by means of a
thick conical elastomer membrane which, when bonded to a support casing
and a central framework to fasten it to the housing to be suspended, e.g.,
the power unit, encloses a chamber containing a damping liquid forced into
an expansion space, under low pressure, through a device with a long
inertial column, with the major portion of the vertical load being borne
by deformation of the elastomer constituting the conical membrane.
French Patent Nos. 2,443,615, 2,462,618, 2,467,724 and 2,511,105 (Peugeot)
describe devices which fit this definition and which have the advantage of
being integratable into the elastic apparatus with a damping column, which
is fitted in a rigid wall immersed in the hydraulic circuit. Thus
constituted, the device after being sealed, e.g., by crimping on an
attachment cover for the casing, of the mounting, thereby manifests itself
as a one-piece component.
Various improvements have been made to these devices. For example, the
device based on a hydrodynamic braking nozzle (French Patent No. 2,430,546
to Chrysler) includes a displacement of liquid aided by a resonant mass,
acting as an inertial damper Others relate to the use of the mass of the
liquid itself, and an adjustment of the characteristics thereof, thereby
making possible a low rigidity in response to vibrations at frequencies
higher than 25 Hz. Low rigidity in this frequency range is effective for
general soundproofing, and also provides good damping at the suspension
frequencies, that is, in the range of 5 to 15 Hz, where disturbances
become noticeable to passengers, as soon as the amplitude of the movements
communicated to the supported structure exceeds one millimeter.
French Patent No. 2,575,253 for this type of hydraulic shock absorber,
called a "column mounting", specifies the simultaneous existence of a
secondary passage having different throttling characteristics than the
principal throttling passage.
An analysis of the prior art shows that it apparently does not include
hydroelastic mountings with a long liquid column which is possibly even
longer than the length of an annular passage and which passage can easily
be adjusted to accommodate the hydroelastic mounting.
All of the above-mentioned patents are hereby expressly incorporated by
reference as if the entire contents thereof were fully set forth herein.
2. Object of the Invention
The object of the invention is to provide a hydroelastic mounting with a
structure having a passage for receiving the damping liquid, which passage
is housed in the rigid partition between the variable volume chamber and
the expansion space of a hydroelastic mounting. The length and/or cross
section of this passage can be adjusted to substantially, precisely
regulate the strokes and frequencies necessary for use in particular
applications, by acting on the mass of liquid contained in this passage
and on the surface of the boundary layer sheared during the alternating
movements of the liquid.
SUMMARY OF THE INVENTION
Using identical constituents, with the exception of the rigid partition,
i.e., for the same dimensions of the variable volume chamber and the
expansion space, and for the same rigidity of the thick conical membrane
constituting the deformable wall, the invention proposes to create a range
of hydroelastic mountings with damping characteristics adapted to each
application, under economic conditions which allow fabrication in small
quantities, by acting on the parameters of the column of damping liquid,
i.e., its cross section and/or its length.
The elastic anti-vibration isolation mounting with integrated hydraulic
damping which is the object of the invention is characterized by the fact
that:
it comprises a passage, consisting of one or two parts, and designed to
contain the damping liquid;
this passage, when it consists of a single part, is constituted either by a
spiral or by a helix, which allows the length of the passage to be greater
than a corresponding circumferential portion being disposed at
substantially the same distance from a central portion of the rigid
partition as the spiral or helix;
the passage, when it consists of two parts, may be constituted of either
two overlapped spirals having the same center, or two overlapped helixes
having the same axis;
the dimensions (length and/or cross section) of the passage for damping
liquid can be adjusted by simple mechanical means such as removal of
material from at least one of the two parts of the rigid partition,
appropriate processing, which may include molding to size, lapping,
grinding, finishing, lathe-working, or the like, the insertion of a shim
between the base and the cover of the rigid partition, or the rotation of
one of these constituents in relation to the other, to adjust the column
of damping liquid to the desired frequencies for different applications.
The different processes for the adjustment of the dimension of the passage
for damping liquid, taken separately or in combination in certain cases
where compatible, are as follows:
To change the length of the passage, it is possible:
to change the diameter of the boring where it opens onto rigid partition,
by appropriate processing, which may include boring, grinding and/or
lathe-working. This process is applicable to a passage consisting of one
or two parts, in the form of a spiral or spirals;
to offset the boring, in the case of a passage in two parts, in the form of
spirals. The length is then adjusted independently over both parts of the
passage;
to use the rotation of the cover in relation to the base of the rigid
partition, at the time of assembly, in the case of a passage for damping
liquid in one or two spiral parts The adjustment of the length is then the
same for both spiral parts of the passage.
To change the cross section of the passage for damping liquid, it is
possible:
to perform a flat processing, such as, grinding or lathe-working, of at
least one of the assembly surfaces of the base and of the cover of the
rigid partition, which results in a reduction of the cross section of the
passage, in one or two parts, in the form of a spiral or spirals or a
helix or helixes, the adjustment of the two spiral or helicoidal parts
then being the same;
to perform an oblique grinding or lathe-working of at least one of the
assembly surfaces of the base and of the cover of the rigid partition,
which is advantageous for the reduction of the cross section of the
passage when it consists of two parts, in the form of spirals or helixes,
by making it possible to adopt a different adjustment for each of the
spirals or helixes;
the insertion of a flat shim between the base and the cover of the rigid
partition, which makes it possible to increase the cross section, a
process which is applicable when the passage for the damping liquid
consists of one or two parts, in spirals or in helixes (the adjustment of
the two parts of the passage then being the same);
the insertion of an oblique shim between the base and the cover of the
rigid partition, which is advantageous for a passage in two parts, in the
form of a spiral or spirals or a helix or helixes, by making it possible
to adopt a different adjustment for the increase of the cross section of
each of the spirals or helixes. One aspect of the invention resides
broadly in an elastic, anti-vibration, isolation apparatus having
hydraulic damping, the apparatus for elastically mounting a first
component to a second component, the apparatus comprising: an arrangement
for mounting the apparatus on a first of the components, the arrangement
for mounting being disposed at one portion of the apparatus; another
arrangement for mounting the apparatus to a second of the components, the
second arrangement for mounting being disposed at another portion of the
apparatus; the first arrangement for mounting having bonded thereto an
elastomeric component; the elastomeric component forming one end of the
apparatus; a rigid partition disposed within the apparatus and separating
the apparatus into at least a first chamber and a second chamber, the
first chamber being disposed between the rigid partition and the
elastomeric component, the first chamber being substantially filled with
damping fluid and comprising a chamber in which damping fluid therein is
subject to compressing and other forces for varying the volume thereof,
the first arrangement for mounting and at least a portion of the
elastomeric component being disposed for moving at least with relationship
to the rigid partition; the rigid partition having two sides, a first side
being disposed towards the first chamber, and a second side being disposed
towards the second chamber; the second chamber comprising an expansion
chamber for at least accepting damping fluid from the first chamber, the
second chamber also being substantially filled with damping fluid; the
rigid partition having disposed therein at least one passage having
dimensions for conducting damping fluid between the two chambers; the
rigid partition comprising at least two components, the at least one
passage extending in at least one of the at least two components for
passing damping fluid between the first side and the second side of the
rigid partition; the at least one passage having a length dimension
substantially greater than a cross section dimension thereof; an
arrangement for varying at least one dimension of the at least one
passage; and the dimension varying arrangement being chosen from at least
one member of the group consisting essentially of: a) at least one surface
of the rigid partition having been dimensionally adjusted by removing at
least a portion of the at least one surface during manufacture to obtain
given dimensions; and b) an arrangement for receiving shim between the
first and second components of the rigid partition, and also including a
shim for insertion into the arrangement for receiving the shim between the
first and second components of the rigid partition; the arrangement for
varying dimensions of the passage between the two chambers being tuneable
to desired damping characteristics for tuning the elastic anti-vibration
apparatus to at least one given frequency characteristic.
BRIEF DESCRIPTION OF THE DRAWINGS
The characteristics and variants of the invention are explained in greater
detail in the description accompanying the drawings, in which:
FIG. 1 is a schematic diagram of the elastic mounting with integrated
hydraulic damping, and identifies the rigid partition which houses the
passage for damping liquid;
FIGS. 2a, 2b and 2c illustrate one particular configuration of the rigid
partition in which the passage for the damping liquid is realized in a
single part in the shape of a spiral, more particularly, FIG. 2a is a
section view of the rigid partition, FIG. 2b is a top view of the base and
FIG. 2c is a bottom view of the cover;
FIGS. 3a, 3b, 3c, 3d, 3e, 3f and 3g show one variant of the rigid partition
in which the passage for the damping liquid is realized in two parts
having the shape of two overlapped helixes, with the safe axis;
FIG. 4 shows another variant of the rigid partition in which the passage is
enlarged by a shim having a spiral cut therein, which shim is inserted
between the two parts of the rigid partition;
FIG. 5a shows yet another variant of the rigid partition with an oblique
shim disposed between the two parts thereof;
FIG. 5b shows the base of the rigid partition of FIG. 5a, in plan;
FIG. 5c shows the cover of the rigid partition in plan from the top
thereof;
FIG. 5d shows FIG. 5a with the oblique shim, in section;
FIG. 5e shows the base of the rigid partition with the oblique shim mounted
thereon, as seen in plan from above;
FIG. 6 illustrates one particular configuration of the rigid partition
similar to FIG. 3b in which the passage for the damping liquid is realized
in the shape of an extended helix; and
FIG. 7 shows the base in plan with a dual spiral.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows, in vertical section, the elastic mounting with integrated
hydraulic damping, and identifies the rigid partition 1 in the elastic
mounting formed by a deformable thick conical membrane 2, designed to bear
the load by strain in shearing of the elastomer compound of which it is
made, and which connects the internal rigid frame 3 to the structure of
the vehicle, such as, the chassis, and the external rigid frame 4 to the
power unit, such as, the motor, of the vehicle.
The damping liquid fills the variable volume chamber 5 and an expansion
space 6 where a very low overpressure, that is, pressure above ambient, is
maintained by deformation of the flexible membrane 7.
To provide damping during operation of the elastic mounting, the damping
liquid is transferred from the variable volume chamber 5 to the expansion
space 6, through the opening 9, via the passage 8 housed in the rigid
partition 1, and forming part thereof.
In the invention, the prefabricated rigid partition 1 is formed by two
assembled rigid elements, preferably made of polymer materials, each
molded in its desired shape. The molding of these elements is preferably
done using conventional processes of the polymer transformation industry,
as is well known in the prior art.
One spiral is shown in FIG. 1; in an alternative embodiment analogous to
the one of FIG. 7, more than one spiral could be realized.
FIGS. 2a, 2b and 2c illustrate one particular configuration of the rigid
partition 1 in which the passage for damping liquid 8 manifests itself as
a single passage having the shape of a spiral in the partition 1.
FIG. 2a is a cross section of the rigid partition 1, comprising a base 10
and a cover 11. This rigid partition 1 differs from the rigid partition in
FIG. 1, where, in FIG. 1, as a function of the desired cross section of
the passage for damping liquid, the base 10 and the cover 11 of the rigid
partition 1 can have the same geometry of the passage 8. The only
substantial differences between the base 10 and the cover 11 are that the
base 10 has pins in relief, protruding therefrom and the cover 11 has
recessed housings or holes in locations corresponding to the pins for
accepting same The positions of the opening 9 and the boring 11a are also
different in the base 10 and the cover 11.
In the illustrated variant, in FIG. 2a of the rigid partition 1, the base
10 houses the entire passage for damping liquid 8, while the cover 11 has
a flat surface which, during assembly, comes into contact with the base
10.
Communication between the damping liquid circuit and the variable volume
chamber takes place via the opening 9 located at the beginning of the
passage 8, while communication with the expansion space takes place via a
ground, variable diameter C of 1, the boring 11a in the rigid partition 1,
both in the base 10 and in the cover 11, i.e., such grinding being
possible after assembly of these two components of the rigid partition 1.
The axis of the variable diameter C of the boring 11a in the rigid
partition 1 does not necessarily coincide with the axis of the
hydroelastic mounting, since its axial offset does not modify the volume
of damping liquid displaced by the deformation of the variable volume
chamber.
FIG. 2b shows a plan view of the base 10 of the rigid partition 1 before
assembly with the cover 11. It shows the spiral shape of the damping
liquid passage 8, the length of which is greater than one circumference,
and the eight assembly pins 12 shown here, as non-limiting examples, which
fit into recessed housings, with the same number and arrangement, in the
cover 11. Other methods of assembly well known in the art, such as,
bonding or other fastening by a cementing compound may be used.
The grinding or lathe-working of the diameter C of the boring 11a which is
tangentially disposed with respect to the spiral, constituting all of
one-half of the passage for damping liquid 8, depending on the
configuration selected for the cover 11, is advantageously performed on
the rigid partition 1 after assembly; the mass production of the rigid
partition 1 produced by molding a polymer such as a 6-6 polyamide
reinforced with glass fibers or glass spheres, can be highly automated.
FIG. 2c shows, looking at the bottom thereof, the variant of the cover 11
of the rigid partition 1 exhibiting one flat surface which, during
assembly, is placed in contact with the base 10. This figure illustrates
the arrangement of the recessed housings 13, the number of which is the
same as the number of pins 12 on the base 10.
The adjustment of the hydroelastic mounting to the desired damping, by the
selection of the shape and size of the passage for damping liquid 8, makes
it possible to respond to given utilization conditions such as, for
example, the vibration frequency introduced by the masses not suspended by
the suspension (or by the motor when the hydroelastic mounting is designed
for the suspension of a truck cab).
With all rigidities otherwise equal, the manufacturer of hydroelastic
mountings can change the mass of the damping liquid column to shift the
frequency at which the apparent maximum damping is produced, by phase
displacement between the speed and the acceleration, while measuring
forced vibrations.
An increase in the diameter C of the boring 11a being cut into the rigid
partition 1, with a constant cross section of the column of damping
liquid, reduces the length of the spiral-shape passage 8; the mass and the
surface area of the boundary layer of the column of damping liquid are
reduced proportionally. The result is an increase of the frequency at
which the damping is maximum, accompanied by a reduction of the damping
rate and the phase displacement.
The reverse results, obviously, are observed for a reduction of the
diameter C of the boring 11a in the rigid partition 1, with a constant
cross section of the column of damping liquid.
A reduction of the depth of the passage for damping liquid 8 can be
achieved by removing a portion of the assembly plane of the base 10, for
example, by spot facing, (according to the embodiment of FIG. 2a), and/or
the cover 11, (according to the embodiment of FIG. 1), of the rigid
partition 1. This has the effect of reducing the mass of the damping
liquid column, similar to that caused by the increase in the diameter C of
the boring 11a in the rigid partition 1, but with a reduction of the
surface of the boundary layer in contact with the walls of the passage for
damping liquid 8. Corresponding to equal displacement of the deformable
walls, constituted by the thick conical membrane 2 of the hydroelastic
mounting, is a given instantaneous flow and an inversely proportional
acceleration of the displacements of the damping liquid in the column with
a reduced cross section.
The relative effect of the damping and the phase displacement increases
with an increase in frequency, in contrast to the results obtained by
modification of the diameter C of the boring 11a in the rigid partition 1.
If the flat grinding or lathe-working of the assembly surface of the base
10 and of the cover 11 of the rigid partition 1 makes it possible to
reduce the cross section of the passage for damping liquid 8, there are
applications where, when the opposite effect is desired, it is desirable
to increase the cross section of the passage. To do this, a flat shim is
inserted between the base 10 and the cover 11 of the rigid partition 1, as
in FIG. 4. The thickness of the flat shim will, obviously, be limited by
the space available between the variable volume chamber and the expansion
space.
The combination of the adjustments of the diameter C of the boring 11a and
of the depth of the passage for damping liquid 8 therefore makes possible
a very precise adjustment of the maximum efficiency of the hydroelastic
mounting as a function of the conditions of utilization.
In applications which require an expansion of the frequency ranges, a
variant configuration (not shown) of the damping liquid passage allows two
different adjustments, thanks to the realization of the passage in two
parts, in the shape of spirals, wound one inside the other, as shown in
FIG. 7, by offsetting the boring C, which will intersect the first spiral
along a developed length less than that along which it intersects the
second spiral. For this reason, the two resonant effects, combined with
the maximum displacements, will allow an optimal damping over a wider
range of frequencies.
It is also possible, for certain particular applications, to realize the
configuration of the passage for damping liquid 8 in two spirals, an
adjustment with two maximum damping values.
This effect can be obtained either by offsetting the boring, as indicated
above, or by modification of the cross sections of the two spiral shaped
parts of the passage for damping liquid 8.
A reduction of the cross section of at least one of the two parts of the
passage 8 is obtained by oblique grinding or lathe-working, as shown in
FIG. 5d, of the assembly surface of the base 10 and of the cover 11 of the
rigid partition 1, while an increase of the cross section of the passage 8
is made possible by the insertion during assembly of an oblique shim
between the base 10 and the cover 11 of the rigid partition 1. These
processes make possible the modification of the cross section of one of
the spiral shaped parts of the passage for damping liquid 8, independently
of the other part. If the same modification of the cross section is
desired for both spiral shaped parts of the damping liquid passage 8,
there are two possibilities open to the design of the part: a flat
grinding or lathe-working of the assembly surface of the base 10 and of
the cover 11 makes it possible to reduce, simultaneously, the cross
section of the two spiral shaped parts of the passage 8, while the
insertion of a flat shim between the base 10 and the cover 11 of the rigid
partition 1 during assembly will make it possible to increase
simultaneously the cross section of the two spiral shaped parts of the
passage 8.
As in the case where the passage consists of a single part in the shape of
a spiral, it is possible to change the length or the two spiral shaped
parts of the passage 8 by grinding or lath working the boring where they
empty onto the rigid partition 1. The manufacturer of hydroelastic
mountings, on account of the design of the rigid partition 1, can
therefore, change three parameters of the circuit for damping liquid,
which will allow him to make the adaptations during assembly of the
components of the hydroelastic mounting, for several types of motors or
suspensions, with different loads, while being able to benefit from the
advantages of mass production of the components, i.e., a reduced
production cost and a greater adaptability to evolutions of
characteristics, the components being all identical for the different
models of a given product, with the exception of the rigid partition 1
which is adjustable, and which can also be mass produced.
FIGS. 3a, 3b, 3c, 3d, 3e, 3f and 3g show one variant of the rigid partition
1 in which the passage for damping liquid 8 no longer consists of two
coiled spirals, but two helixes, show cylindrically here, but they can
also be conical, overlapped one inside the other, and the coiling over
more than one revolution is obtained by a slight slope of each of the
helicoidal parts the passage for damping liquid 8 in relation to the axis
10a of the rigid partition 10
FIG. 3a shows a cross section along BOB' in FIG. 3b of the rigid partition
1 in which the cover 11 is shown with the same general geometry as the
base 10, the main difference between these two components being the
presence of the assembly pins, e.g., located on the base 10, and designed
to fit into the corresponding recessed housings or holes 13 in the cover
11.
FIG. 3b is a schematic diagram of the position of the two helicoidal parts
8a and 8b of the passage for damping liquid in the base 10 of the rigid
partition 1 which contains the assembly pins 12.
Various methods make it possible to modify, simultaneously or
independently, the length and/or cross section of the double column of
damping liquid and, consequently, to change the damping characteristics of
the hydroelastic mounting.
Thus, for example, an angular shift during assembly of the base 10 and of
the cover 11 of the rigid partition 1, e.g., a rotation of the base 10 by
one or more pins 12 in relation to the corresponding recessed housings or
holes 13 on the cover 11, simultaneously modifies the cross section of a
portion of the two helicoidal parts 8a and 8b of the passage for damping
liquid, a well as the useful length of the column of damping liquid
between the two openings 9a and 9b, and their corresponding openings in
the cover 11, thereby allowing a different adjustment both of frequency
and phase displacement, for the apparent damping of the dynamic rigidity
exhibited by the hydroelastic mounting.
This means of adjustment by angular shifting of the base 10 and of the
cover 11 of the rigid partition 1, with respect to one another, does not
change the external dimensions of the rigid partition.
Other adjustment possibilities consist of modifying the thickness of the
rigid partition 1 and are limited to values compatible with the
installation of the rigid partition in the body of the hydroelastic
mounting.
To simultaneously reduce the cross section of the two helicoidal parts 8a
and 8b of the passage for damping liquid, it is possible to perform a flat
lathe-working of the assembly surface of the base 10 and of the cover 11
of the rigid partition 1, e.g., by lathe-working or grinding the surface
of the cover 11 with the preferably, blind holes or recessed housings
designed to receive the assembly pins 12.
The insertion between the base 10 and the cover 11 of the rigid partition
1, during assembly, of a flat shim, such as shown in FIG. 4, makes it
possible, by contrast, to simultaneously increase a portion of the cross
section of the two helicoidal parts 8a and 8b of the passage for damping
liquid.
It is also possible to change, separately, the dimensions of the two
helicoidal parts 8a and 8b of the passage for the damping liquid, either
by performing an oblique grinding or lathe-working of the assembly surface
of the base 10 and of the cover 11 of the rigid partition 1, the effect of
which may be to reduce a portion of the cross section as well as the
useful length of the double column of damping liquid. This arrangement
provides a means to obtain different values for each of the two helicoidal
parts 8a and 8b of the passage for damping liquid. Alternatively, an
oblique shim with a slight slope, can be inserted between the base 10 and
the cover 11, during assembly of the rigid partition 1, the effect of
which may be to increase the cross section and the useful length of the
double column of damping liquid to different values for each of the two
helicoidal parts 8a and 8b of the passage for damping liquid.
The rigid partition 1 with a helicoidal passage can be simplified in a
variant (not shown) comprising a passage consisting of a single part, for
certain applications. The processes to adjust the dimensions of the
helicoidal passage are then limited to the angular shifting of the base 10
in relation to the cover 11 of the rigid partition, during assembly, to
the flat grinding or lathe-working of the assembly surface of the base 10
and of the cover 11 or to the insertion, between the base 10 and the cover
11, of a flat shim of a thickness limited to values compatible with the
installation of the rigid partition 1 in the hydroelastic mounting.
One embodiment of the hydroelastic mounting, as shown in FIG. 2a, in the
configuration where the rigid partition 1 includes a one-part passage for
the damping liquid 8 is described below, the adjustment method selected
being the grinding or lathe-working of the boring 11a.
FIG. 3c shows another embodiment of the section through COD of FIG. 3b. In
this figure, one hole in base 10 is denoted as 19b', and this hole 19b' is
connected through a passage 18b' in base 10, and through a corresponding
passage in cover 11 to a hole 19b" in the cover 11.
FIG. 3d shows a variant of FIG. 3b with reference numeral denotations of
FIG. 3c, and section lines BOB', COD, COB' and BOD.
FIG. 3e shows a section through FIG. 3d along the line BOB'. The rigid
partition 1 in this figure shows only one passage which is composed of
18b' and 18b" for clarity.
FIG. 3f shows a section COB' of FIG. 3d. This Figure, 3f, shows only one
passage which is the connection of the opening 19b' with the passage 18b".
Any other passages in the rigid partition 1 have been omitted for purposes
of clarity.
FIG. 3g shows a section BOD through FIG. 3d. As in FIGS. 3e and 3f, only
one passage is shown. As in all of FIGS. 3e, 3f and 3g, the passages 18b'
and 18b''of the two parts, base 10 and cover 11, are shown by dotted
lines.
FIG. 4 shows a shim 20 disposed between the base 10 and cover 11. This shim
has a spiral cut therein which increases the cross section of the passage
8 in the base 10.
FIG. 5a shows an alternative embodiment of the rigid partition 1. In this
embodiment, the rigid partition 1 is made up lathe-worked or ground such
that at least one of the base 10' or Of a base 10' the cover 11' is
somewhat wedge shaped. Between these two original portions of the rigid
partition 10, that is, the base 10' and the cover 11', an oblique shim 120
is disposed. This oblique shim 120 has holes therein which accept the pins
21 of the base 10' such that the pins 21 protrude through the oblique shim
120 into blind holes in the cover 11'. For simplicity and clarity, the
pins 21 and the holes are not shown. The base 10' has a hole 119b' in the
bottom surface thereof which connects to a passage 118b'. This passage
118b' is aligned with a hole 122 in the oblique shim 120 (shown in FIG.
5a). This hole 122 in the shim 120 is preferably somewhat larger than the
opening which passage 118b' makes on the upper surface of the base 10'.
This hole 122 in the oblique shim 120 connects passage 118b' to a passage
118b " in the cover 11'. This hole 122 in the oblique shim 120 is also
preferably somewhat larger than the opening which the passage 118b" makes
in the lower surface of the cover 11'. This passage 118b" connects with a
hole 119b" in the upper surface of the cover 11'. Only one passage
comprises 118b', the hole 122 and the passage 118b" of the preferably two
passages in the rigid partition 1 is shown in FIG. 5a.
FIG. 5b shows a top view of the base 10' in the rigid partition 1 as shown
in FIG. 5a. As can be seen from this figure, the passage 118b' of the base
10' is shorter than the corresponding passage in FIG. 3d.
FIG. 5c shows a top view of the cover 11' with only one of the holes, hole
119b", shown therein. Connected to this hole 119b" is the passage 118b",
The cover 11' is shown rotated in the position for assembly in the rigid
partition 1, such that, the opening of 118b''is aligned with the hole 122
in the oblique shim 120, as shown in FIG. 5a.
FIG. 5d shows the oblique shim 120 in section in the rigid partition 1. The
oblique shim 120 is also preferably made of a plastic material which may
preferably be similar to the material of the base 10' and the cover 11'.
However, other materials may be used for the oblique shim 120 than for the
other parts of the rigid partition 1.
FIG. 5e shows the oblique shim 120 placed on the upper surface of the base
10'. As can be seen, the hole 122 in the shim is somewhat larger than the
opening formed by the passage 118b' in the base 10'.
FIG. 6 shows a helicoidal passage in the base 10, which when assembled with
a similar cover 11, extends more than one revolution around the partition
1.
FIG. 7 shows a base 10 with two spiral passages 8a and 8b disposed in
partition 1. The boring C is offset from the center of base 10 to provide
damping at two frequencies.
The hydroelastic mounting is produced by assembling the components,
manufactured separately, in the following sequence:
first of all, in a molding operation common in the rubber industry, the
assembly constituting the internal rigid frame, the elastomeric conical
membrane and the external rigid frame is made on a press, followed by an
intimate bonding of these three elements simultaneous with the
vulcanization of the elastomer compound;
independently, in a molding operation, the flexible wall which encloses the
expansion space is realized;
the components, base and cover, of the rigid partition are also fabricated,
these components being realized by molding polymer material, possibly
reinforced, in molds of the desired shapes for the passage for the damping
liquid and to produce the pins or the recessed assembly housings, in the
base or the cover, respectively;
the subsequent operation comprises the assembly of the base and the cover
to form a closed unit or cassette, this assembly being advantageously
produced by ultrasonic welding;
the boring where the spiral or helicoidal damping passage or passages empty
is then ground or lathe-worked to adjust its length;
the constituent elements of the hydroelastic mounting are then assembled,
and a crimping operation completes the assembly in the form of a rigid
casing. If the crimping is performed using the so-called "submarine"
method or technique, the filling of the hydroelastic mounting with the
damping liquid takes place during the same operation. The "submarine"
method is described in U.S. Pat. No. 4,893,799 (Attorney Docket No.
NHL-KLE-0l), entitled "Vibration Isolation Apparatus", corresponding to
French Patent Application No. 8700762, filed Jan. 23, 1987, which is
hereby expressly incorporated by reference as if the entire contents
thereof were fully set forth herein.
On page 5, line 16, to page 6, line 11, of U.S. Pat. No. 4,893,799, there
is stated therein the following:
"In another aspect, the invention features a process for manufacture of a
vibration isolation apparatus. The process comprises the steps of: a)
providing a first subassembly, the first subassembly comprising an
internal tube member, a first intermediate tube member and first flexible
lateral end wall apparatus, the internal and the first intermediate tube
members being maintained in spaced and concentric alignment by their
mutual attachment to the first flexible lateral end wall apparatus; b)
providing a second subassembly, the second subassembly comprising an
external tube member, a second intermediate tube member and second
flexible lateral end wall apparatus, the external and second intermediate
tube members being maintained in spaced and concentric alignment by their
mutual attachment to second flexible lateral end wall apparatus; c)
submerging the first and second subassemblies in a bath of a damping
fluid; d) removing substantially all air bubbles from the submerged first
and second subassemblies; e) concentrically and axially mating the first
and second subassemblies, such that, in the assembled configuration, the
internal tube member is positioned substantially concentric with and
within the second intermediate tube member, the second intermediate tube
member is positioned substantially concentric with and within the fist
intermediate tube member, and the first intermediate tube member is
position substantially concentric with and within the external tube
member; and f) maintaining the concentrically and axially mated first and
second subassemblies in the assembled configuration."
On page 17, line 6 to line 29, U.S. Pat. No. 4,893,799 there is stated
therein substantially the following:
A preferred process for the fabrication of such a device consists of
performing the following operations:
The two assemblies, illustrated, are produced by pressure casting with a
heat treatment which simultaneously vulcanizes the elastomer compound and
produces a bond between the elastomer compounds and the rigid internal,
intermediate and external tubes, which act as frameworks, according to a
process conventionally used in the rubber transformation industry.
An assembly operation, using a so-called "submarine" assembly press, makes
it possible to join the tube assemblies from which all the air bubbles
have been expelled. The end of the rigid intermediate tube is freely
engaged over the rigid internal tube, while the preferably bevelled end of
the rigid intermediate tube is engaged in the rigid external tube, until
the thin layer of elastomer compound and the elastomer compound film
prevent further penetration.
A fitting force is exerted, then, by staggered circular stops which are
provided on the external edge of each of the rigid tubes, at a regulated
rate, so that an appropriate internal pressure is maintained by the
characteristic rigidity of the elastic lateral walls. (end of substantial
quote)
A variant filling of the hydroelastic mounting with the damping liquid
consists of using a vacuum technique in the vessel by providing a lateral
boring in a rigid casing, which is then sealed by a rivet.
The anti-vibration isolation device with integrated hydraulic damping which
is the object of the invention and is designed to provide elastic
suspension of drive units of vehicles or truck cabs has the advantage,
over the solutions of the prior art, that it makes it possible, using
identical components; to create an extended range of hydroelastic
mountings adapted to each application, because of the insertion, during
assembly, of a rigid partition comprising at least one damping liquid
passage adapted, or adaptable, in length and cross section, to the damping
function to be performed.
Because of this design, it is therefore possible to realize economically,
even in limited quantities, a wide variety of hydroelastic mountings with
integrated hydraulic damping, which are perfectly adapted to the
requirements of individual applications.
In summing up, the elastic anti-vibration, isolation, apparatus which has
integrated hydraulic damping therein comprises an elastic mounting. This
elastic mounting has a thick conical membrane 2 made of an elastomeric
compound. This thick conical membrane is bonded to a rigid internal frame
3 and to a rigid external frame 4 and crimped in a rigid casing. This
structure encloses a damping liquid acting such that the inertia of the
column of damping liquid provides a damping function which has desirable
damping characteristics. The length of this column of damping liquid is
very long in relationship to its average cross section. The rigid
partition 1 which separates the variable volume cylinder 5 from the
expansion space 6 has a passage 8 which forms the inertial column and
receives the damping fluid. The passage 8 is formed by one or two parts.
The dimensions of these parts can be adjusted by lathe-working or grinding
of at least one of these parts, that is, the base 10 or the cover 11 of
the rigid partition 1. The dimensions of the passage can be adjusted
during manufacture either as an alternative to the lathe-working or by the
lathe-working of the base 10 or the cover 11 to form a slightly wedge
shaped configuration and then by the insertion of at least one shim
between the base 10 and the cover 11. The two alternatives, the first
being lathe-working at least one of the base 10 or cover 11, and the
second being the insertion of shims therebetween, make it possible, using
a set of substantially identically shaped components, which comprise the
base 10 and the cover 11, to provide a series of hydroelastic mountings
with different damping characteristics, which may be adapted to the
utilization frequencies of the isolation apparatus, or, in other words,
the working of the components 10 and 11 allow for the use of substantially
standard components, which can then be adjusted to provide the desired
damping characteristics for the isolation apparatus.
Another aspect of the invention resides in that the base 10 and cover 11,
which constitute the rigid partition 1, have substantially similar
geometry. This geometry may include the outer portions of the base 10 and
the cover 11. Alternatively, the base 10 and the cover 11 may have a
passage made up of one or two parts for receiving the damping fluid. The
base 10 also has assembly pins 12 designed to fit into corresponding holes
or recesses 13 in the cover 11. In the event that the spiral passage is
distributed between the base 10 and the cover 11, these parts are
substantially identical.
Another further aspect of the invention relates to that only the base 10 of
the rigid partition 1 has a passage for damping fluid therein. The cover
11 has a flat surface which, during assembly, is placed in contact with
the upper surface of the base 10. The cover 11 is held in place by the
pins 12 protruding upwardly from the base 10 into the corresponding holes
13 of the cover 11.
Yet another aspect of the invention relates to the fact that the rigid
partition 1 includes a passage 8 which is made up of either one or two
parts. At least one of these parts has a length which is greater than that
of a corresponding length of one complete revolution around the rigid
partition 1. This configuration can be seen in FIG. 6, where the passage
formed by the base 10 and the corresponding passage in the cover 11 have a
length, when assembled, of more than one revolution. Also, in FIG. 2b, the
spiral shown therein, which comprises the passage 8, extends more than one
revolution around the rigid partition 1.
Still yet a further aspect of the invention provides a passage 8 for the
damping fluid comprising a single spiral, as shown in FIG. 2b.
Still yet another aspect of the invention provides that the passage 8
comprises a single helix.
Yet still another aspect of the invention provides that the rigid partition
1 has a passage which is made up of two parts 8a and 8b. In this case,
there are two passages in the shape of overlapping spirals, such as
indicated in FIG. 7. These overlapping spirals emanate from a
substantially similar central location in the rigid partition 1.
Yet a further aspect of the invention provides for two overlapping helixes
which form at least two passages in the rigid partition 1, as shown in
FIG. 3a. These two overlapping helixes are preferably formed about the
same axis in substantially the middle portion of the rigid partition 1.
There may be, in an alternative embodiment, more than two helixes.
Moreover, even in this case, these helixes preferably also are formed
about the same central axis 10a.
Still a further aspect of the invention provides for the regulation of the
dimensions of the passage 8 which may be for in one or two parts, such
that the shape of a spiral or spirals is done by boring a hole 11a having
a diameter C. This boring 11a is placed to vary the shape or the length of
the spirals to adjust these to a desired characteristic of length or cross
section. This hole 11a is placed in the rigid partition 1 where the
passage 8 is desired to empty from the rigid partition 1.
Yet still another aspect of the invention provides that the boring or hole
11a of the immediately above paragraph, as shown in FIG. 7, can be offset
in such a way that if there are two spirally shaped parts 8a and 8b, which
make up the passage in the rigid partition 1, the lengths thereof can be
regulated independently one of the other. By regulating the dimensions or
each of the two spirally shaped parts 8a and 8b independently, the damping
of the isolation apparatus can be adjusted for two difference frequencies,
one resulting from each of the spirally shaped parts 8a and 8b.
Still an additional aspect of the invention provides that the helicoidal or
helical parts, 8a and 8b of FIG. 3b, which make up the passage for the
flow of damping fluid between the chambers, can be adjusted by angular
rotation during assembly or the base 10 with respect to the cover 11. The
base 10 and the cover 11 can be adjusted by the rotation of one with
respect to the other so that a difference set of pins 12 in the base 10
are aligned with a different one of the holes 13 of the cover 11. Because
the openings, in the cover 11 and the base 10, which connect the passages
of one with the other, extend over at least two of the pins 12, at least
two positions of the cover 11 with respect to the base 10 can be attained.
If a greater number of adjustments are required, a greater number of pins
12 than the six shown in the figures can be used, which will allow for
indexing of the cover 11 with respect to the base 10 by a greater number
of rotational displacements therebetween. For example, if twelve pins are
used instead of the six in FIG. 6, then at least four positions can be
made operationally available for adjustment of the cover 11 with respect
to the base 10. This adjustment would change the length and parts of the
cross sections of the passages extending through the rigid partition 1.
Still yet another additional aspect of the invention provides the
capability of changing the cross sections and/or also the lengths of the
two spiral or two helical parts 8a and 8b of the passage 8 by the oblique
removal of at least one of the mating surfaces of the base 10 and the
cover 11. The two spiral or two helical parts can thus be varied to
achieve optimum damping at least two difference frequencies.
Yet still another additional aspect of the invention relating to the
elastic, anti-vibration, isolation apparatus with integrated hydraulic
damping provides that the adjustment of the cross sections of the
connection or connections between the two sides of the rigid partition 1
can be achieved by lathe-working or grinding of at least one of the
surfaces which are mated between the base 10 to the cover 11. By such
lathe-working or grinding, the spiral or spirals or helix or helixes can
have their cross sections adjusted simultaneously.
Yet still a further additional aspect of the invention provides that the
cross section of the passage in the rigid partition, which may be formed
as a spiral or spirals or as a helix or helixes, can be adjusted by the
insertion, during assembly, of a flat shim between the base 10 and the
cover 11. This flat shim provides for the simultaneous adjustment of at
least the length of, and even in some embodiments, portions of the cross
sectional area of the at least two passages, when there are two or more
passages in the rigid partition 1.
The invention as described hereinabove in the context of the preferred
embodiments is not to be taken as limited to all of the provided details
thereof, since modifications and variations thereof may be made without
departing from the spirit and scope of the invention.
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